FIG. 1 illustrates a method of manufacturing a plug that can be used in a cellular phone. Such a plug comprises a card body and a module. A module comprises a microcircuit and protective resin. The module is generally manufactured independently of the card body and tested separately. If the test is satisfactory, the module is embedded in the card body of an ISO card. The card body is then pre-cut in the format of a GSM plug. In a second testing step, the microcircuit is then tested again. This second test can also be carried out after the embedding but before the cutting. An ISO card provided with a pre-cut outline in the format of the plug is thus obtained. Before use, the plug is separated from the ISO card by the end user. Thus the GSM plugs are manufactured in a discontinuous manner.